Eccentrically-pivoted armature mounting for vibratory units



July 10, 1928. 7 1,676,380

G. F. BORKMAN ECCENTRICALLY PIVOTED ARMATURE MOUNTING FOR VIBRATORY UNITS Filed March 31, 192s \\\\\illl I l gnmmtoo 6.5.802KRAN,

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Patented July 10, 1928.

UNITED STATES PATE roFFreE. v

GEORGE E. BORKMAN, OF sAL T LAKE CITY, UTAH.

Application filed March 31, 1926. Serial No. 98,835.

This invention relates to an eccentrically pivoted armature mounting for vibratory units, and more particularly to an armature such as is used to actuate the diaphragm in sound producing and reproducing devices,

such as microphones or telephone and radio receivers, and its principal objects are:

First. To overcome the reactanceand lag of the armature; U I

Second. To substantially eliminate the ungoverned vibration of the free end of the armature, thereby reducing the natural vibration thereof, caused by the applied energy, in coming back to the normal position. p

Third. To cause the armature to vibrate through a smaller angle, thereby approacl1- ing more nearly a parallel action, than is the case with the center pivoted armature.

Fourth. To cause the applied energy tov exert a greater influence upon the diaphragm.

Fifth. To reduce the bending anoment upon the pins where rigidly mounted pin mountings are used.

Sixth. To make possible the use of aheavier and more durable armature.

In attaining the objects just outlined, any desired method of pivoting the armature may be used, the pivot being. placed to one side of the center plane of the electromagnet, but interjacent the polar extremities of the armature.

lVhile most of the advantages obtainable through the use of this invention accrue, no matter what particular method of mounting may be employed, yet, where the well known rigid pin mounting is used, the additional advantage of reducing the bending moment upon the pivot pins, is an important consideration. The armature may. be rigidly mounted upon the pivot pins in the usual manner and the pins be rigidly fastened in the spool sleeve of the electromagnet in the customary manner. Similarly, the link connection from the diaphragm to the armature, may be of any desired type.

The features of this invention for which the protection of Letters Patent is desired, are collectively grouped in the claims concluding this specification.

In the drawing which illustrates merely one embodiment of this invention,

Fig. 1 represents a vertical center section through a radio receiver, the electromagnet thereof being shown in cross-section.

Fig. 2, a top plan, partly in section on line 2-2 in Fig. 1; and

F ig. 3, a diagram drawnto an enlarged scale, and indicating the relative movement ot the armature arranged in accordance with the present invention, compared to the movement of an ordinary centrally pivoted armature.

Referring to the drawing, 10 indicates the usual permanent magnet within which may be mounted the electromagnet, whose coil 12,

pivot pins 17, which in turn are also rigidly securedto the armature 18.

The broken line 19 indicates the longitudinal vertical center plane of the electro. magnet. It will be noted that the pivot pins 17 are located to one side of the plane 19, and upon the far side from the pin connection 20, which latter extends from the arn1aturc 18 to thediaphragm 24, this location giving rise to the term eccentrically pivoted. Attention is directed to the fact that in all other sound producing or reproducing devices with which I am familiar, the pivot pins would be located in the center plane 19. a

In the present instance is shown the auxiliary pin 21 which extends from the outer end of the short arm of the armature to the pin connection 20, but this forms no part of the presentinvention, as the same is the subject of my appending application for U. S. patent, filed April 11,1925, Serial No. 22,474. It is shown here to make known its adaptability to, and use with, the present invention.

When the armature 18 is actuated by the energized electromagnet coil, it oscillates through an angle, indicated for convenience, as, who in the diagram, (Fig. 3). In this figure mm indicates the center or neutral position. ofthe armature. It is convenient to use the same figure to compare the results of mounting the armature in the ordinary centrally pivoted manner, with the results of mounting it in the eccentric manner of the present invention. lVhere the armature is fastened to the pins 17, in Fig. 1, is indicated by b in Fig. 3, and the fastening of the pivot pin in the spool sleeve 16, is indicated .is held by the usual pole pieces 14 and 15. l/Vithin the sleeve'16 of the spool on which coil 12 is wound, are the rigidly secured.

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ivoting of the armature ma, the angle afc indicates the hunt of oscillation thereof, a? and g representing the extreme positions of the. armature. The line 7% represents the It is obvious that he angle aim is considerably less than the angle afc, and also that the angles eZcl and gkh are respectively equal to the angles ate and aft.

Comparing the'actions of the two methods of mounting the armature ma, we will consider first its center pivoting at Supposing the end m of the armature to be in its central position, the electromagnetic action upon both extremities of the armature will cause the armature to be jerked about the centerof oscillation is and the free end on to flop through angular space in an un governed way, this resulting in. a reactance and lag upon the sound vibrations of the diaphragm.

The action of the armature mm when mounted on the eccentric pivot pin bl as in the present invention, the end m again being supposed to be pivoted to the diaphragm, would be to oscillate around the center Z leaving only the short arm Zm ungoverned, thus reducing the objectionable reactance and lag very materially. Where the auxiliary pin 21 is connected to the short arm, this small reactance and lag would be reduced to almost zero.

' It is obvious that the flexing of the pivot pin bl acting through the angle eZd would be much less than the flexing of the pivot pin acting through the angle gica, thereby lengthening the life of the pivot pin and its fastenings materially.

Owing to the length of the lever arm mb compared with the length my", the armature in the eccentrically pivoted form may be made of heavier material than in the centrally pivoted form.

WVhile a typical embodiment of this invention is herein shown and described, it should be clearly understood that all the detailed parts thereof, may or may not, appear in the. preferred forms, and also, that the preferred forms may be varied from time to time, depending upon the circumstances and conditions governing and governed by, the development of this invention and the arts to which it is incident, therefore the scope of this invention may be ascertained from the claims in which its spirit is generalized. 1

Having fully described my invention, what I claim is: V

1. A vibratory unit comprising a spool having a sleeve with its winding, armature. mounting pins eccentrically located Within the said" sleeve, and an armature operatively mounted upon said pins.

v 2. A vibratory unit comprising a sleeve and a coil wound upon said sleeve, rigidly disposed pivot pins eccentrically located within said'sleeve and an armature rigidly fastened to the said pivot pins.

3. In an eccentrically pivoted armature mounting, an electromagnet spool having a sleeve, pins projecting inwardly from said sleeve, said pins being spaced apart from each other along a line lying between the open ends of said sleeve, said line being spaced apart from the center line lying between said open ends, and an arn'iature mounted on said pins.

l. An armature and mounting, comprising a supporting structure, pivots secured in said structure, and an armature mounted on said pivots, the points at which said ar mature is connected to said pivots lying in a straight line located between the polar extremities of the armature, said line being spaced apart from the line lying midway between the said armature extremities.

5.,In an eccentrically pivoted armature mounting, an armature, pole pieces having polar extremities in proximity to both ends of said armature, and a pivotal mounting for said armature, the pivotal axis lying interjacent the ends of the armature and interjacent the said polar extremities, but to one side of the longitudinal vertical center plane between said polar extremities.

In testimony whereof, I sign my name hereto.

GEORGE F. BORKMAN. 

